Transformer-based systems may be used to provide data communication and/or power transfer across a galvanic isolation barrier. Exemplary fields of application of these systems are the industrial field (e.g., gate drivers), the medical field (e.g., implantable devices), and more generally, sensors, lighting and other areas where galvanic isolation may be helpful.
The need is therefore felt for improved arrangements for transmitting power and data via a transformer.
Several examples of data communication in galvanically isolated systems are disclosed e.g. in: a) S. Wayne, “iCoupler® Digital Isolators Protect RS-232, RS-485, and CAN Buses in Industrial, Instrumentation, and Computer Applications”, Analog Dialogue 39-10, October (2005) (incorporated by reference); b) U.S. Pat. No. 8,364,195 and c) ISO8200B—“Galvanic isolated octal high-side smart power solid state relay” STMicroelectronics Datasheet, April 2014 (incorporated by reference). For instance, multiple transformers may be used to implement multiple isolated channels for bidirectional communication and isolated power links as disclosed e.g. in: d) Baoxing Chen—“iCoupler® Products with isoPower™ Technology: Signal and Power Transfer Across Isolation Barrier Using Microtransformers”, 2006 available at http://www.analog.com/isoPower (incorporated by reference), e) U.S. Pat. Nos. 7,983,059, 7,489,526 and 7,706,154 (incorporated by reference), and f) United States Patent Application Publication No. 2012/0256290 (incorporated by reference). An arrangement as described in United States Patent Application Publication No. 2015/0180528 (incorporated by reference) may exploit a same isolation transformer to implement power transfer and bidirectional/half-duplex data communication, possibly by resorting to an oscillator topology as disclosed in United States Patent Application Publication No. 2014/0292419 (incorporated by reference).
In such a system, data communication may be available (only) when power is being transferred, which militates against the possibility of controlling the output power level by on-off switching e.g. with a periodic PWM control, as desirable in various applications (e.g., gate drivers) or when a variable power level may facilitate covering a wide range of products with a same device (e.g., in an isolated interface).